Good question. Does anyone here know a good probiotic and prebiotic combo that will actually repopulate the gut?
Live culture foods such as kefir, miso, tempeh, sauerkraut, etc. are your best choices for probiotics.
Forget most "live culture" yogurts since most are not live culture despite what the packaging says. They were live culture prior to being pasteurized, but no longer.
And the problem with capsuled probiotics in large part is that there is no guarantee they are still live. The reason is that there is no way to tell how long the bacteria were stored, how they were stored and if they were subjected to heat during shipment. All of these can affect the potency of the probiotics. Again, live culture foods are the best with diets providing fiber to feed the flora.